JPH04238025A - Metal plate for partial restriction type damping press molding - Google Patents

Abstract

PURPOSE:To provide a low cost damping material having characteristics usable in each part of a car and excellent in damping properties, press moldability, weldability, rigidity and productivity. CONSTITUTION:A metal plate 1 for partial restriction type damping press molding has a resin layer 2 having damping properties and adhesivenss formed on the single surface thereof and is laminated to a steel plate 4 constituting a car body before press molding at a predetermined position within the range of at least 2% or more in the area ratio of the metal plate to the steel plate area of each part.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a metal plate for partially constrained vibration damping press forming used for automobile noise prevention.

0002

[Prior Art] For noise prevention, if it were possible to take measures against sound sources in addition to measures against air-borne noise that block generated noise, it would be possible to
Since it is very advantageous both technically and economically, there is a demand for the development of vibration damping materials with high performance that can absorb vibrations that cause noise. Based on these backgrounds, domestic and foreign chemistry,
We also develop and market vibration damping materials for paint, nonferrous metal, and steel manufacturers. Furthermore, the damping steel plates currently used to reduce noise in automobiles can be broadly classified into the following two types. One of them is a very thin viscoelastic resin 5 (with a thickness of 50 μm to 100 μm) between two steel plates 3 and 4, as shown in FIG.
This is called a constrained vibration damping steel plate, which is made by sandwiching and crimping the steel plates 4 and 4, as shown in Figure 3.
Thick viscoelastic resin 6 (damping sheet thickness 2 mm to 4
This is called a non-constraint type vibration damping steel plate that is used by pasting a material (approximately 100 mm).

0003

[Problems to be Solved by the Invention] The above-mentioned constrained vibration damping steel plate has superior vibration damping performance compared to the non-constraint type vibration damping steel plate, and not only has a large loss coefficient, but also has a peak characteristic temperature at room temperature and high temperature ( You can freely choose between 80℃ and 100℃). However, when press-forming automobile parts, the viscoelastic resin between two steel plates tends to be sheared and deformed, resulting in creases, commonly called seagulls, on the surface of the steel plate after pressing. As a countermeasure to this problem, modifying the viscoelastic resin will change the damping performance. Furthermore, since the viscoelastic resin is electrically insulating, electric welding such as spot welding cannot be performed as it is. As a countermeasure to this problem, a method has been adopted in which a large amount of nickel beads, stainless steel powder, etc. are kneaded into the viscoelastic resin to impart electrical conductivity, but this increases cost and reduces workability.

[0004] Furthermore, in order to improve the damping performance of non-constrained damping steel plates, a damping sheet with a thickness of 2 mm to 4 mm is generally pasted, but the thick film makes press forming impossible and welding impossible. Therefore, currently only the steel plate is attached after press forming. Furthermore, even if pasted after press molding, if the paint goes through the baking process during the automobile manufacturing process, it will easily sag at high temperatures due to the physical properties of the resin used.
Easy to slip off. Therefore, the productivity of the automobile manufacturing process is significantly hindered. In addition, the viscoelastic resin used in this case is generally inexpensive, but due to its thick film, a large amount is used.
This increases cost and weight, which impedes efforts to reduce the weight of automobiles. Furthermore, even if it is a thick film, it does not have the same strength as the mechanical test value of a steel plate, so it has various drawbacks such as being inferior in rigidity to a constrained vibration damping steel plate.

[0005]

[Means for solving the problem] As mentioned above, both constrained vibration damping materials and non-constrained vibration damping materials have their own problems. Damping properties as a vibration damping material that can be used (damping performance with different peak characteristic temperatures is required depending on the parts used), press formability, weldability, rigidity, corrosion resistance, productivity (automation and labor saving possible) ), low cost, etc., the configuration of the present invention is as follows. A metal plate having a resin layer having vibration damping properties and adhesive properties on one side of the steel plate that constitutes the vehicle body before press forming is applied in an area of at least 2% or more in terms of area ratio of the metal plate to the steel plate area of each part. The metal plate for partially restrained vibration damping press forming is characterized in that the metal plate is laminated at a predetermined position.

[0006] However, the inventors have found that regarding vibration damping properties,
It is sufficient to have the function of absorbing the energy of the noise-generating parts themselves and converting them into thermal energy, damping the vibration velocity or vibration amplitude, and reducing acoustic radiation. There is no need to restrict the entire area of the steel plate used for floors, dashboards, wheelhouses, partitions, roofs, etc., especially for parts related to living spaces. The idea was that the same vibration damping performance could be obtained regardless of the size of the product, and after much research was carried out by changing some of the restraints in each component, the results were proven to be exactly as expected. Therefore, considering the automation and labor saving of the automobile production process, such partially constrained vibration damping materials are made of metal that has a viscoelastic resin layer on one side on the surface of a steel plate that is sheared to a blank size before being press-formed into each part. It was determined that it was necessary to pre-glue the boards in place. In other words, this position not only needs to be considered to be a position that is effective for vibration damping, but also needs to be designed to avoid welding points, and it is even more effective if it is located at a position that can assist the rigidity of the part. found. In addition, when partially restraining in this way, the periphery of the bonded metal plates will form dents on the back surface of the steel plate of the part during press forming, so care must be taken in the position of partial restraint.

As mentioned above, the position, area, and shape of partial restraint differ depending on each part, but according to experimental results, the total area of partial restraint at each position of the part is at least 2 of the area of the steel plate of each part. It has been found that all of the above-mentioned requirements for a vibration damping material can be satisfied by partially restraining % or more. Therefore, the area of the metal plates to be bonded together is small, resulting in a significant cost reduction. Furthermore, it is sufficient for the viscoelastic resin layer coated on one side of the metal plate to have a thickness of about 50 μm from the viewpoint of vibration damping properties. However, since it is partially attached to a steel plate before press forming, it is necessary to have both vibration damping properties and adhesive properties.

Furthermore, since the viscoelastic resin layer is electrically insulating, the electrocoating paint does not adhere to the surface of the metal plate even if it passes through a cationic electrocoating tank during the automobile manufacturing process, so it is suitable for parts that require high corrosion resistance. It is necessary to pre-coat the metal plate with a paint that has the same performance as the electrodeposition paint. Further, it is also possible to use an aluminum plate or an aluminum alloy plate as the metal plate due to the corrosion resistance of the cut portion and weight reduction. Furthermore, considering the additional effect of rigidity, it is preferable to use an aluminum alloy plate whose mechanical test value is comparable in strength to that of a steel plate, and the weight effect is also significant.

[0009]

[Operation] The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a sectional view showing a state in which a metal plate 1 according to the present invention is laminated to a steel plate 4. A metal plate 1 having a viscoelastic resin layer 2 at a position that avoids welding points for each part of an automobile, such as a floor, a dashboard, a wheel house, a partition, etc., takes press formability into consideration, and takes into account rigidity effects.
pasted together. The damping performance of the sample after press forming was measured by varying the ratio of the area of the partially restrained metal plate to the area of the steel plate of the part. This measurement method was performed by the impact method. This method uses a microphone to record the sound after impact on a sample on a sound level meter, and determines the degree of attenuation of the noise level from the change over time.
D; dB/S) and resonance frequency (fn; Hz) to calculate the loss coefficient (η), generally η = D/27.3f
It is represented by n. As a result, compared to parts made by press-forming conventional restraint-type damping steel plates, partially restraint-type vibration damping materials differ depending on the part, but if at least 2% or more of the steel plate area of each part is partially restrained in terms of area ratio, they are exactly the same. The loss coefficient was obtained. Furthermore, by increasing the restraint area, not only the vibration damping performance but also the rigidity effect was significantly improved.

[0010] As for the resin with vibration damping and adhesive properties that is coated on one side of the metal plate in advance, any viscoelastic resin that absorbs vibration energy through shear deformation and exhibits a sound reduction effect can be used. This is possible, and is not particularly defined by the present invention. However, thermoplastic resins generally used as viscoelastic resins include ethylene copolymers and/or diene copolymers. Examples of this ethylene copolymer include ethylene/vinyl acetate copolymer, ethylene/α-olefin copolymer, ethylene/vinyl acetate/vinyl chloride terpolymer, ethylene/vinyl chloride copolymer, ionomer, and ethylene/propylene. There are copolymers, ethylene/propylene terpolymers, etc. In addition, diene copolymers include butadiene-styrene copolymers, styrene-styrene copolymers,
There are butadiene-styrene copolymers, etc. Unsaturated polyester resins are often used as thermosetting resins,
Petroleum-based hydrocarbon resins may be aromatic, aliphatic, or synthetic polyterpene-based, but aromatic-based resins with a high softening point are particularly desirable; coumaron-indene resin, pt-
Butylphenol/acetylene resin, novolak resin,
Terpenes, phenolic resins, etc. are used. However, since a metal plate having a viscoelastic resin layer is partially attached to a steel plate, adhesive strength becomes an important issue. This may be any polymeric material that has polar groups that provide strong adhesion to the steel plate. If the viscoelastic resin used does not have polar groups, these polymeric materials should be blended into the viscoelastic resin in advance or used. It is preferable to use two layers of a polymeric material having a polar group that is compatible with the viscoelastic resin. As mentioned above, a wide range of resins with vibration damping and adhesive properties can be used to coat metal plates, but since they are painted and baked after press molding in the automobile manufacturing process, their viscosity is extremely high up to at least 170°C. Resins that degrade and do not run down should be used. Furthermore, if a resin whose viscosity is extremely reduced at high temperatures is used, problems tend to occur, such as the viscoelastic resin at the bottom of the metal plate sagging or the metal plate slipping and falling after the paint is baked.

[0011] Corrosion at the interface between the viscoelastic resin layer of the metal plates bonded together and the lower steel plate poses a problem in order to improve the durability of the completed automobile. Corrosion under the paint film can be prevented as the adhesive strength of the paint film increases, but anti-corrosion treatment of the steel sheet surface is also important. If a steel plate or a plated steel plate is subjected to a chemical conversion treatment such as phosphate treatment or chromate treatment, it is possible to prevent the progression of corrosion under the paint film, but this is not desirable in terms of cost. A simple and effective way to reduce costs is to mix anti-corrosion pigments such as zinc chromate or strontium chromate into the adhesive resin when using a viscoelastic resin or when bonding in two layers. Even with steel plates without chemical conversion treatment, it is possible to prevent a decrease in adhesive strength due to corrosion under the paint film. In experiments, it was found that if at least 2% or more of these anticorrosive pigments were mixed into the resin, the resin could withstand long-term corrosion tests.
However, if too much anti-corrosion pigment is mixed, the physical properties of the resin will deteriorate, making it impossible to achieve the original purpose of these resins, such as vibration damping properties. In addition, the metal plates used for partial restraint improve the rigidity of each automobile part, so even if the elongation is set to the minimum value that allows each part to be press-formed, the tensile strength is set to the highest possible value. metal plates should be used.

As mentioned above, a steel plate having a metal plate bonded via a viscoelastic resin at a predetermined position that avoids welding points and has an effect on vibration damping and rigidity is press-formed and then welded according to the automobile manufacturing process. It is assembled into a white body, undergoes chemical conversion treatments such as degreasing and phosphate treatment, and then is immersed in a cationic electrodeposition tank. Since the viscoelastic resin is electrically insulating, no electrodeposition paint is applied to the surface of the metal plate. Therefore, metal plates used for parts that require high corrosion resistance are pre-painted metal plates (
Although it is necessary to use a painted steel plate, painted steel plate, etc., it is most desirable to use a high-strength aluminum thin plate from the viewpoint of corrosion resistance of the end cut and weight reduction. Aluminum plates have excellent corrosion resistance as is, and if a coating such as an intermediate coating is applied on top of them, they exhibit even better corrosion resistance. Furthermore, if an aluminum alloy plate with high tensile strength and yield strength is used, the effect of rigidity can be achieved even if the plate thickness is thin.

[0013]

[Example] An example applied to a dashboard will be described. A compound made by kneading ethylene/vinyl acetate copolymer, butadiene/styrene copolymer, and strontium chromate as materials with vibration damping, adhesive, and rust prevention properties is melted in an extruder and extruded through a T-die to form a film. It was coated on one side of a metal plate to a thickness of 70 μm. The metal plate used has a tensile strength of 44 kgf/
High-strength aluminum-magnesium alloy plate with a thickness of 0.23 m and a yield strength of 39 kgf/mm2 and an elongation of 7%.
The coil was 914 mm in length and board width. Approximately 3cm x 30cm, 4cm x 34cm, 12c from the coated coil
Punch out three almost rectangular pieces of about m x 14 cm, and before pressing, the board thickness is 0.8 mm x board width 1000 mm x length 20
It was pasted at the marked position on the 00mm steel plate. The location was determined through numerous research tests to avoid welding parts of the press-formed dashboard parts, and was determined to be the most effective location for vibration damping and rigidity. Thereafter, a steel plate with small pieces of aluminum alloy plate attached at three locations with viscoelastic resin was press-formed into a dashboard. The area ratio of the total area of the three partially restrained vibration-damping metal plates bonded to the steel plate area of the dashboard is approximately 3.5%.
Met. Welding was carried out to assemble it to the car body, but since the aluminum alloy plates were pasted together avoiding the welded areas, the process was completed smoothly under normal welding conditions. After that, degrease, wash,
Although it went through the steps of chemical conversion treatment, cleaning, cationic electrodeposition painting, and baking, no peeling of the bonded metal plates or sagging of the viscoelastic resin occurred during the process. The adhesion to the steel plate actually improved during the baking process after electrodeposition coating. After applying the intermediate coat and baking, the dashboard was removed from the vehicle body and the following quality confirmation tests were conducted. As a comparative material, a restrained vibration damping steel plate made by sandwiching a viscoelastic resin containing nickel beads of 60 μm in thickness between two steel plates with a thickness of 0.4 mm in order to make it weldable was used in the same process. The vibration damping performance is as mentioned above.
It was measured by the impact method. 3.5% area ratio compared to the fully restrained type
Exactly the same loss coefficient was obtained for the partially constrained type. Rigidity was measured by supporting both ends of the dashboard and applying a concentrated load to the center, using a beam test method supported at both ends.
30% better rigidity than the comparative material was obtained. Furthermore, the corrosion resistance was determined by a JIS salt spray test. Although the surface of the partially restrained metal plate was not electrodeposited with cationic electrodeposition paint and was only coated with an intermediate coat, it exhibited far superior corrosion resistance compared to the comparative materials. In particular, there was no rust leaching from the cut edges, which are the peripheral edges of the metal plate, and an excellent difference was observed compared to the comparative materials. Furthermore, the cost of dashboard parts using a partially restrained vibration damping metal plate was reduced by more than 35% compared to the cost of manufacturing a dashboard using a conventional restraint type vibration damping steel plate.

[0014]

[Effects of the Invention] As described above, a viscoelastic resin layer is applied to a steel plate before press forming to form each part of a car body at a predetermined position that avoids welding points and has an effect on vibration damping. By partially pasting them together in advance, they can be used in various processes such as press forming, welding car body assembly, degreasing, chemical conversion treatment, electrodeposition painting, baking, intermediate coating, baking, top coating, baking, etc. in the automobile manufacturing process. Production has been completed without any problems, and parts using partially restrained vibration damping metal plates not only have excellent vibration damping performance, rigidity, and corrosion resistance, but also achieve significant cost reductions. This has a remarkable effect.

[0015]

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a state in which metal plates according to the present invention are bonded together.

FIG. 2 is a sectional view of a conventional restraint-type damping plate.

FIG. 3 is a sectional view of the conventional non-restrictive vibration damping plate.

[Explanation of symbols]

1 Metal plate 2 Viscoelastic resin 3,4 Steel plate 5 Thin viscoelastic resin 6 Thick viscoelastic resin

Claims (3)

[Claims] Claim 1: A metal plate having a resin layer having vibration damping properties and adhesive properties on one side is applied to the steel plate that constitutes the vehicle body before press forming, and the area ratio of the metal plate to the steel plate area of each part is at least A metal plate for partially constrained vibration damping press forming, characterized in that it is laminated at a predetermined position within a range of 2% or more. 2. The partially restrained type according to claim 1, wherein the metal plate having a resin layer having vibration damping properties and adhesive properties is an aluminum plate, an aluminum alloy plate, a painted aluminum plate, or a painted aluminum alloy plate. Metal plate for vibration damping press forming. 3. The metal for partially constrained vibration-damping press molding according to claims 1 and 2, characterized in that a rust-preventing pigment is added to the resin layer having vibration-damping and adhesive properties that is coated on the metal plate. Board.